1. Field of the Invention
The present invention relates to the transmission of still pictures in a transmission system that uses signals coded according to the MPEG2 standard.
2. Description of the Prior Art
FIG. 16 shows a block diagram of a still picture transmission system according to the prior art. Shown in FIG. 16 are the still picture requesting device 91 provided in the receiver (i.e., the user), the still picture generator 92 provided in the transmitter and used by the program broadcaster (content provider), the still picture transmission request signal line 93 output from the requesting device 91 to the still picture generator 92, the still picture file 94 stored by the content provider in the still picture generator 92, and the still picture data line 95 output by the still picture generator 92.
A still picture transmission service is currently achieved by content providers by means of the still picture transmission system described above operating as follows.
Specifically, when a user makes an individual programming request, the still picture transmission request signal is transmitted through the ling 93 to the still picture generator 92. The still picture generator 92 then searches the still picture file 94 to find the still picture data corresponding to the content of the request signal, and outputs said still picture data through another line 95 to the end user.
With this conventional method, however, a user-to-transmitter communications line 93 is required to send the still picture transmission request signal to the still picture generator 92. While this communications line (channel) 93 can be reserved with relative ease in cable and similar broadcasting systems, it is a more difficult problem in satellite broadcasting systems. Furthermore, even though the data content of the still picture data is relatively small, specifically because it is a still image, it is still necessary to reserve a dedicated transmission channel 95. As a result, the transmission channels 93 and 95 cannot be effectively utilized.